Device for heating process water for a water-carrying household appliance for the care of laundry items, and household appliance having such a device

ABSTRACT

A device for heating process water for a water-carrying household appliance is provided. The device stores thermal energy surrounding the device and transfers the thermal energy to the process water. The device is a latent heat energy store having a heat exchanger with a storage medium and a working medium. The storage medium stores the thermal energy and the temperature of a phase transition of the working medium is set between 20° C. and 22° C.

The present invention relates to a device for heating process water fora water-carrying household appliance, particularly a household appliancefor the care of laundry items.

In washing machines, the water flowing in from a supply network, whichis also referred to hereinbelow as process water, is heated with the aidof an electrical heating device from the inflow temperature up to theset washing temperature. The energy needed for this constitutes a majorpart of the energy needed for a wash cycle. The temperature of theinflowing process water is typically significantly lower than thetemperature of the space in which the household appliance is installed.Thus, in Berlin, for example, the process water supplied to consumerstypically has a temperature at the water meter of between 13° C. and 15°C. Washing appliances are frequently installed in a room insideapartments and buildings. The temperature of interior rooms liestypically between 20° C. and 25° C. and in summer may sometimes liesignificantly above that, and, in particular, even reach up to 30° C. Inan extended period of non-use, all parts assume the temperature of theroom in which they are installed.

A washing machine or dishwasher having a latent heat store which isdesigned for heating supplied fresh water is known from DE 44 03 737 A1.The latent heat store is connected to a heat exchanger, the primarycircuit of which is composed of a line carrying waste water and thesecondary circuit of which is composed of the line for the fresh waterto be supplied, such that heat from the waste water is transferred tothe latent heat store and can be fed again to the fresh water to besupplied. A further such water-carrying household appliance is disclosedin DE 199 60 812 A1.

The object of the present invention is to create an alternative deviceand/or a household appliance with which the heating of process water fora water-carrying household appliance can be carried out in anenergy-efficient and cost-effective manner.

This object is achieved in a device having the features as claimed inclaim 1 and in a household appliance according to claim 17.

An inventive device for heating process water for a water-carryinghousehold appliance which is preferably a household appliance for thecare of laundry items is designed for storing thermal energy in thesurroundings of the device and for transferring the thermal energy tothe process water. The device can thus achieve an energy-efficientheating of the process water for the household appliance, as thetemperature in the surroundings of the device and also of the householdappliance, which temperature is normally higher than that of the processwater is absorbed and transferred to the process water. In an ongoingwashing process, the temperature of the process water in the householdappliance has therefore to be raised only by a significantly smallertemperature value than is the case in conventional household appliances.Thermal energy from the air in the space surrounding the device ispreferably fed to the device for thermal storage. In this way, theprocess water supplied to the household appliance can be heated toambient temperature in a simple manner. The device can be constructedvery simply and cost-effectively since, for example, no secondarycircuit of a heat exchanger known from the prior art is required.

The device is preferably designed as a latent heat energy store. This isparticularly advantageous since the thermal energy absorbed can also bestored in the device and can be transferred as required. In this way,the energy-efficiency can be increased still further.

The device is preferably connected to the water supply network andconnected to the household appliance. Provision is made in this way forthe device to be integrated into the inflow facility, and no additionalexternal further devices thus have to be provided. The device can thusbe integrated into the entire feed system with a minimum of componentsand in an optimum position.

The device is designed, in particular, for accommodating a quantity ofprocess water required for a wash and/or rinse program, in particular atleast 101. This is a particularly advantageous embodiment since in thisrespect a quantity of water such as is subsequently necessary for achosen wash and/or rinse program can be thermally subjected to thestored heat energy. In this way, even very large quantities of processwater can be heated by the device, so that this also impactsadvantageously on subsequent full use during a washing process.

The device is also designed not least with the objectives of being ableto apply thermal energy efficiently specifically to such largequantities of process water and thus also of enabling a relatively largeincrease in the temperature of such large quantities of process water tobe achieved by the device.

In particular, the device is designed to transfer the absorbed thermalenergy to the process water in a deactivated phase of the householdappliance. This energy store is thus loaded in the non-use phase of thehousehold appliance and brought to the temperature in the surroundingsof the device, in particular in a space in which the household applianceis installed. When water flows in, the absorbed energy is transferred tothe inflowing process water.

It is particularly advantageous specifically in this phase to apply thethermal energy to the process water accordingly, as it is then availablefor subsequent use in a wash program at a significantly highertemperature and can be fed to the water-carrying household appliance, inparticular the washing appliance or the household appliance for the careof laundry items.

The device preferably comprises a heat exchanger having a storage mediumfor thermal energy. The device may, in particular, be a latent heatstore having such a heat exchanger. The temperature of the phasetransition of the working medium of the heat exchanger is preferably setto a temperature between 20° C. and 22° C. In the phase of non-use ofthe household appliance the storage medium of the heat exchanger isliquefied through absorption of energy from the installation space. Whenwater flows in, a phase transition of this storage medium occurs, andthe storage medium transfers its latently stored energy to the processwater and/or the inflowing water. A latent heat store of such a designis capable of storing large quantities of energy in a small storagevolume.

In a particularly advantageous manner, the storage medium of a heatexchanger of this type is the inflowing process water itself. The deviceis thus in a particularly advantageous manner designed such that, withregard to this design, the process water itself forms the storage mediumwith regard to this absorption of energy.

The device for heating process water preferably has a container foraccommodating the process water, which container is designed forabsorbing the thermal energy. This design enables direct contact to beachieved between the process water and the container walls, providing adirect thermal coupling via which a particularly effective transfer ofthe stored thermal energy from the container to the process water can beeffected.

In particular, the device is designed such that a container of this typeis arranged externally in relation to the household appliance, inparticular arranged in a built-in furniture unit, in particularintegrated therein. It has proven to be particularly advantageous for acontainer of this type to be built into and integrated in a worktop, thehousehold appliance preferably being located beneath this worktop. Inthis way a device of this kind can be arranged and provided in a manneroptimally suited to the installation space.

Alternatively, the device for heating process water is encompassed bythe water-carrying household appliance itself. It has proven to beparticularly favorable for the device to be integrated in the worktop ofthe household appliance.

A wound, in particular serpentine, flow channel is preferably embodiedin the container. This design enables the guiding of the process waterflowing into the container to be arranged particularly effectively suchthat it comes into contact as much and as often as possible with thecontainer walls, in which the thermal energy is stored through increasein the temperature of the heat of the container. The flow channel can beembodied as a tubular structure in the built-in furniture component, inparticular the worktop. This flow channel is preferably dimensioned soas to accommodate as great as possible a volume of water.

A particularly advantageous embodiment is produced if the flow channelis formed and/or delimited by the inner walls of the container and byadditional separate dividing walls in the container. Virtually theentire interior volume of the container can thus be designed foraccommodating the process water and for forming the flow channel. It isprecisely such a design that on the one hand makes it possible for alarge quantity of process water, for example even as much as 151 ormore, to be accommodated and on the other nonetheless provides this in aparticularly compact and minimally-sized container design.

It is preferably provided that blocking elements, in particular valves,are arranged at the inlet and/or at the outlet of the device, inparticular at the inlet and/or at the outlet of the container. Suchvalves for controlling the water inflow and the water outflow can thusbe arranged upstream of or downstream of the storage device. If thevalve is located upstream of the storage device, it is preferablyprovided that it be ensured through an appropriate arrangement of thestorage device or a special outflow protection that the process waterlocated in the energy storage device, in particular the container, isnot carried further in an undesired manner or does not flow out in anundesired manner after termination of the filling process.

The design of a flow channel in the container prevents the relativelycold inflowing process water from mixing to an undesirable extent withthe previously heated process water located in the container. The inletsand the outlets of the device, in particular of the container, as wellas the flow channel, are preferably arranged and designed such that theinflowing relatively cold process water expels or forces the previouslyheated process water out of the container. As a consequence, thispreviously heated process water then exhibits no undesired cooling bythe inflowing process water.

In the event that the device is arranged externally in relation to thehousehold appliance, a thermal insulation facility is preferablyembodied on a side of the device facing the household appliance. It mayin particular be provided that the facility has a thermal insulationlayer arranged on the inside of the container. Such a design can preventa transfer of heat from the interior of the household appliance to thedevice and an associated condensation of ambient air humidity on theinside. This would extract part of the stored thermal energy again,thereby reducing again the effective transfer of heat for heating theprocess water in the device.

Such thermal insulation facilities may also be provided accordingly onthe device for heating the process water, which device is encompassed bythe household appliance.

It may in particular be provided that, for example, at a temperature ofthe inflowing process water of approximately 15° C. and a temperature ofthe surroundings of the device of approximately 23° C., a water quantityof approximately 151 can be heated such that in a care process of thehousehold appliance, in particular in a washing process, the heatingtime of the supplied process water can be reduced by about four minutes.This leads to a reduction in energy consumption of approximately 0.14kWh. Such a use of a device for heating the process water can alsoachieve improved dissolving of the detergent during the care process inthe household appliance.

The process water heated by the device and flowing into a container ofthe household appliance, in particular into an outer tub or dishwashercavity, has substantially the temperature of the surroundings of thedevice, and consequently less energy and less time are required forfurther heating of the water in the household appliance during theexecution of a care process.

Exemplary embodiments of the invention will be described in greaterdetail hereinbelow with the aid of schematic drawings, in which:

FIG. 1 shows a schematic representation of a household appliance and ofa device for heating process water;

FIG. 2 shows a schematic plan view of an exemplary embodiment of adevice according to the invention; and

FIG. 3 shows a longitudinal sectional representation of the deviceaccording to FIG. 2.

Identical or functionally identical elements are labeled in the drawingswith the same reference characters.

FIG. 1 shows in a schematic front view a household appliance for thecare of laundry items, which is embodied as a washing machine 1. Thewashing machine 1 comprises a drum 2 which is mounted rotatably about anaxis A oriented perpendicularly to the plane of the drawing. The drum 2is designed for accommodating laundry items. The washing machine 1additionally comprises an 3 which surrounds the drum 2 circumferentiallyand into which water and/or a washing liquor is introduced when awashing process is executed.

FIG. 1 additionally shows a built-in furniture unit which comprises aworktop 4. The worktop 4 is arranged in a vertical direction (ydirection) above the washing machine 1, the washing machine 1 beinginstalled in an installation space below the worktop 4.

The embodiment also shows a device 5 for heating process water 8 whichflows in via a supply network 9. The device 5 comprises a container 6which is integrated in the worktop 4. The container 6 has an input orinlet 7 which is connected to a hose connection, the process water 8flowing into the container 6 via this hose and the inlet 7. On theopposite side viewed in a horizontal direction (x direction) thecontainer 6 comprises an output or outlet 10 which is likewise connectedto a hose 11 which leads into the washing machine 1 such that theprocess water flowing out from the container 6 can be routed via thehose 11 and optionally via further components into the outer tub 3.

The device 5 comprising the container 6 is designed for storing thermalenergy 14 (FIG. 2), the walls of the container 6 heating up in thisrespect to the temperature of the surroundings of the container 6 andthus to the temperature in the installation space of the washing machine1, this thermal energy then being transferred in particular via thewalls of the container 6 to the process water 8 located in the container6.

The device 5 comprising the container 6 is designed in particular as alatent heat energy store.

FIG. 2 shows a plan view of the worktop 4 and thus also of the device 5comprising the container 6. The container 6 has an interior space whichenables it to accommodate a quantity of water of, for example, 151. Inthe interior of the container 6 a flow channel 17 is embodied which ispreferably delimited on the one hand by the inner wall 12 of thecontainer 6 and on the other by further dividing walls 13. According tothe embodiment shown in FIG. 2, the dividing walls 13 are orientedparallel to one another and are arranged on the inner walls 12 in such away that a meandering and thus also serpentine winding of the flowchannel 17 through the container 6 is produced. The relatively coldprocess water 8 flowing in via the inflow or inlet 7, which water iscolder in temperature than the ambient temperature in the installationspace of the washing machine 1, is thus guided, so to speak, through theflow channel 17, absorbing the stored thermal energy 14 and being heatedas it does so. In particular, the process water 8 in the container 6then has a temperature which corresponds to the temperature of thesurroundings of the washing machine 1. The washing machine 1 is thusconnected to an energy store and/or a device 5 which heats the inflowingwater. In particular, this device 5 is loaded in a phase of non-use ofthe washing machine 1 and brought to the temperature of the installationspace. When water flows in, the thermal energy absorbed is transferredto the process water 8. The process water 8 flowing via the outlet 10 tothe outer tub 3 has as a result the temperature of the installationspace, and less energy and less time are needed for further heating ofthe water in the washing machine 1.

Thus, in the embodiment shown, a latent heat energy store is shown inwhich the storage medium is the process water 8 itself. In the phase ofnon-use of the washing machine 1, the container 6 is completely filledwith inflowing process water 8 and then both the inlet 7 and outlet 10are closed by means of valves (not shown in detail). The process water 8then located in the container 6 absorbs the stored thermal energy.

If this process water 8 is subsequently needed for a washing process,the valve on the outlet 10 and also the valve on the inlet 7 arepreferably opened and the heated process water 8 located in thecontainer 6 is forced through the flow channel 17 by the relatively coldprocess water 8 flowing in via the inlet 7 and is correspondinglydisplaced and expelled from the outlet 10. The flow channel 17 not onlygenerates the greatest possible degree of contact between the processwater 8 flowing in the container 6 and the inner wall 12 but alsoprevents a relatively large quantity of heated process water 8 in thecontainer 6 mixing with the relatively cold inflowing process water 8and thus can also prevent an undesired intense cooling of a relativelylarge quantity of previously heated process water 8 in the container 6.

FIG. 3 shows a schematic longitudinal sectional representation along thesection AA of the device 5 according to FIG. 2. It can be seen that athermal insulation facility 15 is embodied over the entire surface ofthe base of the container 6, the side 16 facing the washing machine 1thus being thermally insulated. A transfer of heat from the interior ofthe washing machine 1 to the device 5 and thus a possible associatedcondensation of ambient air humidity on the inside of the container 6can thereby be prevented, as a result of which an extraction of heatfrom the heated process water 8 located in the container 6 can also beprevented.

In an alternative embodiment, the worktop 4 shown in FIG. 1 is not anintegral part of a built-in furniture unit but an integral component ofthe washing machine 1, i.e. the worktop 4 comprising the device 5 isrigidly connected to the washing machine 1.

The above-mentioned exemplary embodiments of the device for a washingmachine and of the washing machine itself also apply mutatis mutandis todishwashers.

1-18. (canceled)
 19. A device for heating process water for awater-carrying household appliance, the device to store thermal energysurrounding the device and to transfer the thermal energy to the processwater, wherein the device is a latent heat energy store comprising aheat exchanger with a storage medium and a working medium, wherein thestorage medium stores the thermal energy, and wherein a temperature of aphase transition of the working medium is set between 20° C. and 22° C.20. The device of claim 19, wherein the water-carrying householdappliance is a household appliance for care of laundry items.
 21. Thedevice of claim 19, wherein the device is connected to a water supplynetwork and to the water-carrying household appliance.
 22. The device ofclaim 19, wherein the device accommodates a quantity of the processwater that is necessary for at least one of a wash program and a rinseprogram.
 23. The device of claim 22, wherein the quantity of the processwater is at least 10 liters.
 24. The device of claim 19, wherein thedevice transfers absorbed thermal energy to the process water in adeactivated phase of the water-carrying household appliance.
 25. Thedevice of claim 19, further comprising a container to accommodate theprocess water and to absorb the thermal energy.
 26. The device of claim25, wherein the container has a wound flow channel.
 27. The device ofclaim 26, wherein the wound flow channel is a serpentine flow channel.28. The device of claim 26, wherein the container has an inner wall anda plurality of dividing walls that form the flow channel.
 29. The deviceof claim 19, further comprising an inlet and an outlet, wherein aplurality of valves are arranged at at least one of the inlet and theoutlet of the device.
 30. The device of claim 25, wherein the containerhas an inlet and an outlet, and wherein a plurality of valves arearranged at at least one of the inlet and the outlet of the container.31. The device of claim 19, wherein one side of the device has a thermalinsulator.
 32. The device of claim 31, further comprising a container toaccommodate the process water and to absorb the thermal energy, andwherein the thermal insulator has a thermal insulation layer on theinside of the container.
 33. The device of claim 25, wherein the deviceis external in relation to the water-carrying household appliance. 34.The device of claim 25, wherein the container is external in relation tothe water-carrying household appliance.
 35. The device of claim 33,wherein the device is in a built-in furniture unit.
 36. The device ofclaim 35, wherein the device is integrated in the built-in furnitureunit.
 37. The device of claim 33, wherein the thermal insulator is on aside facing the household appliance.
 38. The device of claim 19, whereinthe device is integrated in a worktop, and wherein the householdappliance is installed below the worktop.
 39. A water-carrying householdappliance, comprising a device for heating process water, the device tostore thermal energy surrounding the device and to transfer the thermalenergy to the process water, wherein the device is a latent heat energystore having a heat exchanger with a storage medium and a workingmedium, wherein the storage medium stores the thermal energy, andwherein a temperature of a phase transition of the working medium is setbetween 20° C. and 22° C.
 40. The water-carrying household appliance ofclaim 39, further comprising a worktop, wherein the device is integratedin the worktop.